1. Field of the Invention
The present invention generally relates to a continuous disreefing apparatus for use with parachutes.
2. Description of the Related Art
Military cargo parachute systems that are used for heavy cargo delivery typically use large diameter parachutes which are reefed to slow their opening, thereby reducing the forces on the entire system. Reefing cargo parachutes typically require the use of expensive pyrotechnic devices, such as cutters, configured with specific time delays. Some systems require multiple stages of reefing and multiple pyrotechnic devices. During each stage of reefing, the partially opened parachute canopy slows the velocity of the payload. Once the pyrotechnic device fires, the canopy will open to the next reefing stage or open fully. When disreefing occurs, a peek force is observed, producing repeated shocks to the parachute delivery system. Referring to FIGS. 1A and 1B, there is shown a prior art, reefed parachute. The reefed parachute canopy 10 is reefed by reefing line 12 which is attached to parachute skirt 14 by reefing rings 16 located at the attachment point of each suspension line 18. Reefing line 12 is sized to allow canopy 10 to initially open to some percent of its full, inflated diameter. Canopy 10 will remain in this configuration until pyrotechnic cutter 20 fires and disreefing occurs. This causes canopy 10 to open fully or to the next reefing stage. FIG. 1C illustrates the forces on a typical prior art parachute system over time from deployment to full opening without reefing. FIG. 1D illustrates the forces on the same type of prior art parachute system with a single stage of reefing. The time at which disreefing occurs is indicated by time TD. FIG. 1E illustrates the forces on the same type of prior art parachute system with multi-stage reefing. The times at which disreefing occurs are indicated by times TD1 and TD2. The forces illustrated in FIGS. 1C-1E demonstrate peak and repeated shocks to the parachute system even when reefing is employed.
What is needed is an apparatus that provides continuous, smooth and consistent disreefing that causes the parachute canopy to open slowly and reduce or minimize peak and repeated shocks on the parachute system.